System and Method for Analyzing Dynamic CPU Voltage

ABSTRACT

Systems and methods are disclosed for monitoring a voltage supplied by a voltage regulation module to a processor in response to a dynamic VID generated by the processor. In one embodiment, a voltage monitoring system monitors the voltage generated by the voltage regulation module to ensure the supplied voltage is within regulation thresholds. The voltage monitoring system acquires an analog reading of the supplied voltage and converts it to a digital value. If the VID changes during the conversion, the result of the A/D conversion is discarded. If the VID does not change, the voltage monitoring system accepts the result of the A/D conversion and compares the supplied voltage to the voltage expected in response to the VID. The voltage monitoring system may compute the error between the actual and expected voltage for each accepted A/D conversion. These errors may be accumulated and averaged. The accumulated error may be compared with regulation thresholds, such as a predefined allowable margin of error. If the accumulated error exceeds regulation thresholds, an alert may be generated and action may be taken depending on the degree and severity of the accumulated error.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to monitoring and regulating the voltagesupplied by a voltage regulation module to a processor in response to adynamic VID.

2. Description of the Related Art

In the past, CPUs functioned on a static voltage. The static voltagesupplied to a CPU could be monitored and easily compared to the expectedvoltage to make sure the supplied voltage was within a specified marginof error from the expected voltage. Now, CPUs are designed to operate ondynamic (variable) voltages driven by a voltage regulation module (VRM).A variable-voltage CPU outputs a dynamic “voltage identification” signal(VID) to the VRM in order to specify the voltage that the CPU requiresat each moment. The VRM generates a dynamic voltage in response to thedynamic VID. The dynamic nature of the VID output presents uniquechallenges for monitoring the voltage to ensure proper regulation.

A microcontroller that is responsible for verifying that the CPUreceives the correct voltage from the VRM must be able to compare theactual voltage with the voltage expected for the current VID.Accordingly, the microcontroller will first need to sense the voltageand convert the sensed voltage from an analog value to a digital value.While certain microcontrollers have a built-in analog to digitalconverter (i.e., an A/D converter), converting a voltage reading from ananalog to digital value takes a considerably long amount of time (forexample, milliseconds) in comparison with the timescale on which a VIDmay change (for example, microseconds). Accordingly, it is quitepossible that the VID output to the VRM will change during an analog todigital conversion of the voltage being supplied to the CPU. Such achange in the VID will promptly cause a resulting change in the voltageand affect the analog to digital conversion. When this happens, thedigital value is not representative of the voltage resulting from theVID.

Therefore, there is a need for an improved system and method formonitoring the voltage regulator module in order to verify that the CPUis receiving an actual voltage that is close to the expected voltage. Itwould be desirable if the system and method could be accomplishedwithout disrupting the normal operation of the CPU and the VRM. It wouldbe even more desirable if the system and method could be implementedwithout requiring any customized or expensive hardware components.

SUMMARY OF THE INVENTION

A first embodiment of the invention provides a method of monitoring adynamic processor voltage. A voltage is supplied to a processor inrelation to the value of a VID output from the processor. An analogvalue of the supplied voltage is converted to a digital value. Anychange in the value of the VID signal during the analog to digitalconversion of the supplied voltage is detected. The digital value of thesupplied voltage and the value of the VID signal during the analog todigital conversion are accepted unless a change in the value of the VIDsignal is detected during the analog to digital conversion. An error iscomputed between the accepted digital value of the supplied voltage anda voltage expected in response to the accepted value of the VID.

A second embodiment of the invention provides a system for monitoring adynamic processor voltage. A voltage regulation module supplies avoltage to a processor in relation to a VID generated by the processor.An analog to digital converter converts an analog value of the suppliedvoltage to a digital value. A change detection module detects any changein the dynamic VID during the analog to digital conversion. If no changein the VID is detected during the conversion, then a validation modulecompares the supplied voltage to a voltage expected in relation to theVID and computes a difference between the expected voltage and thesupplied voltage.

A third embodiment is a computer program product comprising a computerusable medium including computer usable program code for analyzing aprocessor voltage supplied to a processor in relation to the value of adynamic VID signal output from the processor. Computer usable programcode receives a digital value resulting from an analog to digitalconversions of the supplied processor voltage, detects any change in thevalue of the VID signal during the analog to digital conversion, acceptsthe digital value of the supplied processor voltage and the value of theVID signal during the analog to digital conversion unless a change inthe value of the VID signal is detected during the analog to digitalconversion, and computes an error between the accepted digital value ofthe supplied processor voltage and a voltage expected in response to theaccepted value of the VID.

Other embodiments, aspects, and advantages of the invention will beapparent from the following description and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a voltage monitoring system forverifying that a voltage regulation module continuously supplies thecorrect voltages to a CPU in response to VID values generated by theCPU.

FIG. 2 is a graph qualitatively comparing actual and expected voltagevalues over a range of VID values for a hypothetical system.

FIG. 3 is an expanded schematic diagram further detailing the voltagemonitoring system of FIG. 1.

FIG. 4 is a flowchart outlining one embodiment of a method of monitoringa dynamic voltage supplied to a processor in response to a dynamic VIDgenerated by the processor.

FIG. 5 is a schematic diagram of a computer system in which a dynamicCPU voltage may be monitored and analyzed according to an embodiment ofthe invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention includes highly reliable and accurate systems andmethods for monitoring, analyzing, and verifying the proper regulationof a voltage supplied to a processor in response to a dynamic VIDgenerated by the processor. In one embodiment, a voltage monitoringsystem monitors the voltage generated by the voltage regulation moduleto ensure the supplied voltage is within regulation thresholds. Thevoltage monitoring system converts an analog reading of the suppliedvoltage to a digital value. This analog to digital conversion takestime, during which the VID may change. If the VID changes during theconversion, the result of the A/D conversion is discarded as beingpotentially inaccurate and unreliable. If the VID does not change duringthe conversion, the voltage monitoring system accepts the result of theA/D conversion and compares the resulting digital value of the supplied(“actual”) voltage to the voltage expected in response to the particularVID value.

The system may compute the error between the actual and expected voltagefor each accepted A/D conversion. The system may then accumulate theseerrors, and may average them. The accumulated error may be compared withregulation thresholds, such as a predefined allowable margin of error.If the accumulated error exceeds regulation thresholds, an alert may begenerated. Remedial action may be taken depending on the degree andseverity of the accumulated error. Examples of such remedial actioninclude throttling the processor, powering off the processor or thevoltage regulation module, shifting workload from the processor toanother processor in a data center, or even powering off the hardware onwhich the processor and voltage regulation module may reside.Ultimately, the voltage regulation module may need to be replaced if itis determined to be the cause of voltage regulation errors.Alternatively, the processor may need to be replaced if it is determinedto be incorrectly generating the VID.

The invention thereby provides reliable and accurate monitoring ofvoltage in a modern, variable-voltage processor. By monitoring the VIDfor any changes during the A/D conversion of each voltage reading, theaccurate voltage readings (taken during a period in which no VID changewas detected) may be accepted and used for error analysis. Meanwhile,the inaccurate voltage readings (taken during a period in which a VIDchange was detected) may be discarded. By accepting only the accuratevoltage readings for subsequent error analysis, a more complete andcorrect representation of processor and voltage regulation moduleperformance may be obtained.

FIG. 1 is a schematic diagram of a voltage monitoring system (VMS) 10for verifying that a voltage regulation module (VRM) 12 continuouslysupplies the correct voltage to a processor (“CPU”) 14 in response toVID signals generated by the CPU. The voltage to the processor isconsidered to be correct if it is within an allowable margin of error ofthe voltage that is expected for any given VID. The voltage monitoringsystem 10 may be a subsystem of a computer system that includes the VRM12 and the CPU 14. For example, the VMS 10, VRM 12, and CPU 14 may beincluded together on a motherboard. The CPU 14 generates a dynamic VID,which changes over time according to the CPU's changing voltage needs.The VRM 12 attempts to supply the requested voltage corresponding to thevalue of the VID at each moment in time. Thus, in response to eachchange in the value of the VID, the VRM 12 adjusts the voltageaccordingly.

The voltage monitoring system 10 includes an analog to digital (“A/D”)converter 20 for converting analog voltage readings to digital values, achange detection module 40 for detecting any change in the VID valueduring an A/D conversion, and a validation and regulation module 60 forverifying that the supplied voltage is within an acceptable margin oferror of the requested voltage. If there is a VID change during an A/Dconversion, the validation and regulation module 60 ignores the resultof the A/D conversion. If there is no VID change during an A/Dconversion, the validation and regulation module 60 compares the resultof the A/D conversion (which is a digital representation of the suppliedvoltage) to the voltage expected in response to the value of the VIDduring that A/D conversion. The voltage monitoring system 10 may includeone or more presently available microcontrollers, such as a serviceprocessor, having a built-in A/D converter, change detection circuitry,or both. Software such as firmware included with the microcontroller ora driver managed by a computer operating system may provide thenecessary algorithms for monitoring and controlling the supplied voltageaccording to the invention.

The CPU 14 may be capable of generating a discrete set of VID valuescorresponding in one-to-one relationship with a discrete set of voltagevalues. The expected relationship between VID and voltage may bedescribed, for example, by a table or characteristic curve relating eachVID value to its corresponding voltage value for the given CPU 14, whichmay be determined in accordance with VRM design specifications orinitial testing. The expected voltage may be obtained as a “tablelookup” for a given VID value. An electronic table (or its equivalent)may be accessed, which relates the values of the VID to theircorresponding voltage values. The CPU 14 outputs the value of the VIDthat corresponds to the voltage it needs at any point in time. The CPU14 may select the value of the VID to output according to the processingload placed upon it. Also, the CPU 14 may select the value of the VIDwithout necessarily determining the literal voltage value it requires.The VRM 12 may electronically determine the requested voltage byreferring to the table or characteristic curve associated with the CPU14, but most likely the VRM is simply designed via hardware to performin a manner consistent with such a table or curve. An example of acharacteristic VID/Voltage curve for a CPU is included in the graph ofFIG. 2. The VID/Voltage relationship may be a step function, which is apiecewise constant function having only finitely many pieces.

FIG. 2 is a graph qualitatively comparing actual and expected voltagevalues over a range of VID values for a hypothetical system. Thehorizontal axis of the graph is the VID value and the vertical axis isthe Voltage value. The curve labeled “V_(EXPECTED)” is thecharacteristic curve for the CPU of the hypothetical system. TheV_(EXPECTED) curve comprises a set of points that each relates adiscrete VID value (horizontal axis) with its corresponding voltagevalue (vertical axis). Thus, the expected voltage for each VID value canbe determined from the V_(EXPECTED) curve. It should be recognized thatessentially the same information may be kept in a table or otherelectronically storable and electronically accessible format.

The V_(ACTUAL) curve plots the actual voltage supplied by a VRM inresponse to VID values. As shown, the V_(ACTUAL) curve closely, but notexactly, tracks the V_(EXPECTED) curve. The Error shown in the graph isthe magnitude of the difference between the actual voltage and theexpected voltage at a particular VID. Exemplary error analysis equationsare given below the graph. In this case, the % Error is the percentagethat the actual voltage deviates from expected voltage. The AverageError is equal to the sum of the % Error values divided by the number“n” of those values. An acceptable margin of error (+ and −) is alsoshown. In this example, the actual voltages are within the margin oferror, as desired. Other error analysis principles and techniques areknown generally in the art, including a variety of statistical erroranalysis approaches.

FIG. 3 is an expanded schematic diagram further detailing the voltagemonitoring system 10 of FIG. 1. A system clock 15 is included formetering events or actions over time within the system 10. The systemclock 15 generates a clock signal 17 that may be used to coordinate theactions of the system 10, as well as time system events such as A/Dconversions. The A/D conversion module 20 includes a receiver portion 22for receiving an analog reading of the voltage generated by the VRM 12,an A/D converter core 24 for converting the analog voltage reading to adigital value, and a digital output portion 26 for outputting thedigital value to the validation and regulation module 60. The digitalvalue provided by the A/D conversion module 20 may directly indicate thevalue of the voltage. Alternatively, the digital value may require a“table lookup” or mathematical operation to arrive at the actual voltageit represents. In any case, the digital value may be regarded as a“digital equivalent” of the analog voltage reading, in that the voltagemay be determined, either directly or indirectly, from the digital valueconverted from the analog voltage reading.

In one practical embodiment, the A/D conversion module 20 may beincluded with a microcontroller. The A/D conversion module 20 may becapable of performing many A/D conversions in rapid succession.Nevertheless, the speed of the A/D conversions may still be considered“slow” in comparison to the exceedingly fast performance speed of othersystem components and events. For example, each A/D conversion may spana time interval on the order of microseconds or even milliseconds.Meanwhile, the value of the dynamic VID generated by the CPU 14 mayfluctuate more rapidly, such as on the order of nanoseconds, or at leasthas the potential to change before completion of a particular A/Dconversion. Thus, if a particular A/D conversion is begun at a time “T0”and completed at a time “T1,” the VID at T1 may be different than theVID at T0. Alternatively, the value of the VID may be the same at T1 asit was at T0, but may have changed at least once during the A/Dconversion, i.e. between T0 and T1. If such a change in the VID were tooccur during the A/D conversion, the digital value provided by thedigital output 26 would be an unreliable or inaccurate indicator of thevoltage actually requested by the CPU 14 at any particular point in timeduring the time interval from T0 to T1.

The change detection module 40 monitors the VID generated by the CPU 14and detects any change in the VID during each A/D conversion performedby the A/D conversion module 20. The change detection module 40 receivesthe VID as an input. At each time T0, the VID at T0 is stored in a VIDsettings register 42. The VID settings register 42 may be, for example,a set of latches included with a microcontroller. A first comparator 44continuously monitors and compares the value of the VID being receivedfrom the CPU 14 to the value of the VID stored in the register 42. If achange occurs, the first comparator 44 signals a change detectionregister 46 in response. The change detection register 46 may contain achange detection “bit” that can be toggled between binary digits. Forexample, a “0” bit may reflect no VID change, which may be toggled to a“1” bit to indicate a VID change. A reset request element 48 may also beincluded with the change detection module 40. The reset request element48 may be triggered by the validation and regulation module 60 toselectively reset the change detection register 46 at the beginning (T0)of each A/D conversion.

The validation and regulation module 60 is in communication with boththe A/D conversion module 20 and the change detection module 40. Thevalidation and regulation module 60 includes a second comparator 62.Inputs to the second comparator 62 include the value of the VID and thedigital value of the voltage to the CPU 14 during each A/D conversionperiod. The value of the VID may be provided, as shown, by the VIDsettings register 42. Alternatively, the value of the VID may come fromelsewhere in the change detection module 40, or even directly from theVRM 12 at some time during the applicable time interval during which noVID change was detected.

If a VID change is reflected in the VID register 46 during any A/Dconversion, the value of the VID and the digital value representative ofthe voltage may be ignored and discarded. A VID change during the A/Dconversion would otherwise render unreliable any comparison of the VIDoutput by the CPU 14 to the voltage actually supplied to the CPU 14. Ifthese values are discarded, the validation and regulation module 60 mayactivate the reset request 48 to reset the change detection register 46.For example, in response to the reset request 48, the change detectionregister 46 may be toggled from 1 to 0. The validation and regulationmodule 60 may then wait for a subsequent A/D conversion and againperform a check to see if a VID change was reflected during thatsubsequent A/D conversion. This cycle may be repeated as often asnecessary, until the occurrence of an A/D conversion during which no VIDchange is detected.

If no VID change is reflected in the VID register 46 as having occurredduring an A/D conversion, the comparator 62 compares the value of theVID (or, more particularly, the expected voltage corresponding to thevalue of the VID) to the digital value representative of the actualvoltage during that A/D conversion. An acceptable margin of error may bepre-established for a given CPU/VRM pair. In a properly regulatedsystem, the voltage supplied by the VRM 12 will typically be within themargin of error of the voltage requested by the CPU 14. For example,during a particular time interval from T0 to T1, the CPU 14 may requesta desired voltage of 1.5V by outputting a VID value corresponding to1.5V. In response, the VRM 12 may have supplied an average of 1.467V.This error may be expressed as 2.2%=(1.5-1.467)/1.5×100%. The errorafter each target time interval from T0 to T1 may be recorded in anerror register 64. The average error for each time interval during whichno VID change was detected may also be stored in the voltage errorregister 64. The individual errors may then be analyzed in terms of theaverage error, or by using other statistical error analysis techniquesor characteristics known in mathematics, science, and engineering. Theerrors may then be compared to regulation thresholds provided in adatabase 66. The regulation threshold database 66 may be provided, forexample, in a technical specification for a particular microcontrolleron which the system 10 is embodied. A comparator 68 is included forcomparing the voltage errors recorded in the error register 64 to theregulation thresholds specified in the regulation thresholds database66.

The comparator 68 may output a signal 65 representative of thecomparisons it performs and/or of errors recorded in the voltage errorregister 64. This signal 65 may be received by another system orsubsystem for further analysis. For example, the signal 65 may be sentto and processed by management software residing on a workstation thatprovides global management and support for multiple servers. The signal65 may alternatively be output locally to a single computer or device onwhich the system 10 may reside. If the average of the errors recorded bythe voltage error register 64 exceeds the threshold(s) or margin oferror specified in the regulation thresholds database 66, such as+/−10%, then the signal 65 generated may include an alert. This alertmay trigger or at least indicate the need for corrective action, such asa request for a system administrator to swap out faulty components. Forexample, the VRM 12 may be faulty, unable to provide the voltagerequested by the CPU 14 within the margin of error specified by theregulation thresholds database 66. In extreme cases, such as where thevoltage supplied is far in excess of safety requirements, or where aloss of important data is imminent, a more serious, evasive course ofaction may be followed. Evasive action may include, for example,shutting down the CPU 14 and related components or subsystems.

FIG. 4 is a flowchart outlining one embodiment of a method of monitoringa dynamic voltage supplied to a processor in response to a dynamic VIDgenerated by the processor. Reference numerals provided in FIG. 4 forreferring to steps do not imply a required sequence of steps in thenumerical order of the reference numerals. The method may be performedon the system 10 of FIG. 3, for example. The change detection circuit isreset in step 100, such as by setting the change detection bit to 0, sothat any new change can be detected. The voltage supplied to theprocessor in response to the current VID is sensed as an analog value,in that the voltage sensed has a continuously variable quality, and ananalog to digital (A/D) conversion is initiated at time T(0) in step102. In step 104, it is determined whether the analog to digitalconversion is completed. If the A/D conversion is not complete, theprocess loops back to step 104, until the convention is complete. Oncethe A/D conversion completed, then in step 106 the current VID isretrieved. Step 107 includes identifying whether any VID changesoccurred while the A/D conversion was in process. Identifying a changein the VID is typically performed by examining the change detectionregister, such as by noting whether a change detection bit currently hasa value of 1. If any VID changes did occur during the A/D conversion,then the results of the A/D conversion are discarded in step 108, and anew A/D conversion is then begun using the current VID settings (steps100, 102, and 104 are repeated). However, if the VID did not changeduring the A/D conversion, then the raw A/D reading is converted tovoltage in step 110. The voltage that is expected on the basis of thecurrent VID is obtained by a lookup in a known data table or curve, instep 111. Then in step 112, the digital value of the actual voltage andthe expected voltage are compared in order to obtain a percentage errorvalue.

The “expected voltage” is the value of the voltage expected in responseto the VID, which may be obtained from a data table or curve. The errorbetween the expected voltage (as indicated by the VID) and the actualvoltage (as indicated by the digital voltage value) are recorded and theerror is averaged in step 114. It should be recognized that these errorsmay be analyzed by statistical techniques other than taking a simpleaverage. It is then determined whether the average errors, or someanalytical representation of the recorded errors, exceed regulationthresholds in step 118. If the average error does not exceed theregulation thresholds, then the process returns to step 100. However, ifthe average error does exceed the regulation thresholds, then the needfor corrective or evasive action is evaluated in step 120.

This evaluation in step 120 may not necessarily trigger an immediate or“emergency” response. Rather, the circumstances may be weighed in orderto determine the appropriate response, if any. For example, if a systemhas historically performed within regulation thresholds, and the averageerror has gradually grown to slightly exceed the regulation thresholds,an alert may be generated for consideration by a system administratorwithout necessitating immediate action. For example, the systemadministrator may consider over the course of hours, days, or even weekswhether the processor, VRM, or other associated hardware needsreplacement. Alternatively, for example, if the processor suddenly anddramatically shifts from operating well within regulation thresholds tooperating far outside the regulation thresholds, or begins operatingconstantly at the maximum or minimum voltage (or no voltage at all),with little or no correlation to the VID, the exigency of thosecircumstances may warrant the need for more immediate action. Examplesof such action include throttling the processor, shutting down theprocessor, the VRM, of any system on which they reside, shiftingworkload from the processor to another processor in a data center, oreven powering off the hardware on which the processor and VRM reside.

It should be recognized that the invention may take the form of anembodiment containing hardware and/or software elements. Non-limitingexamples of software include firmware, resident software, and microcode.More generally, the invention can take the form of a computer programproduct accessible from a computer-readable medium providing programcode for use by or in connection with a computer or any instructionexecution system. For the purposes of this description, acomputer-usable or computer readable medium can be any apparatus thatcan contain, store, communicate, propagate or transport the program foruse by or in connection with the instruction execution system, apparatusor device.

The medium can be an electronic, magnetic, optical, electromagnetic,infrared, or semiconductor system (or apparatus or device) or apropagation medium. Examples of a computer-readable medium include asemiconductor or solid state memory, magnetic tape, a removable computerdiskette, a random access memory (RAM), a read-only memory (ROM), arigid magnetic disk and an optical disk. Current examples of opticaldisks include compact disk-read only memory (CD-ROM), compactdisk-read/write (CD-R/W), and DVD.

A data processing system suitable for storing and/or executing programcode typically includes at least one processor coupled directly orindirectly to memory elements through a system bus. The memory elementscan include local memory employed during actual execution of the programcode, bulk storage, and cache memories that provide temporary storage ofat least some program code in order to reduce the number of times codemust be retrieved from bulk storage during execution.

Input/output (I/O) devices such as keyboards, displays, or pointingdevices can be coupled to the system, either directly or throughintervening I/O controllers. Network adapters may also be used to allowthe data processing system to couple to other data processing systems orremote printers or storage devices, such as through intervening privateor public networks. Modems, cable modems, Ethernet cards, and wirelessnetwork adapters are examples of network adapters.

FIG. 5 is a schematic diagram of a computer system generally indicatedat 220 that may be configured for monitoring a dynamic CPU voltageaccording to an embodiment of the invention. The computer system 220 maybe a general-purpose computing device in the form of a conventionalcomputer system 220. Generally, computer system 220 includes aprocessing unit 221, which may contain one or more dynamic-voltage CPUswhose voltage is to be monitored according to the invention. Thecomputer system 220 also includes a system memory 222 and a system bus223 that couples various system components, including the system memory222 to processing unit 221. System bus 223 may be any of several typesof bus structures including a memory bus or memory controller, aperipheral bus, and a local bus using any of a variety of busarchitectures. The system memory includes a read only memory (ROM) 224and random access memory (RAM) 225. A basic input/output system (BIOS)226 is stored in ROM 224, containing the basic routines that help totransfer information between elements within computer system 220, suchas during start-up.

Computer system 220 further includes a hard disk drive 235 for readingfrom and writing to a hard disk 227, a magnetic disk drive 228 forreading from or writing to a removable magnetic disk 229, and an opticaldisk drive 230 for reading from or writing to a removable optical disk231 such as a CD-R, CD-RW, DV-R, or DV-RW. Hard disk drive 235, magneticdisk drive 228, and optical disk drive 230 are connected to system bus223 by a hard disk drive interface 232, a magnetic disk drive interface233, and an optical disk drive interface 234, respectively. Although theexemplary environment described herein employs hard disk 227, removablemagnetic disk 229, and removable optical disk 231, it should beappreciated by those skilled in the art that other types of computerreadable media which can store data that is accessible by a computer,such as magnetic cassettes, flash memory cards, digital video disks,Bernoulli cartridges, RAMs, ROMs, USB Drives, and the like, may also beused in the exemplary operating environment. The drives and theirassociated computer readable media provide nonvolatile storage ofcomputer-executable instructions, data structures, program modules, andother data for computer system 220. For example, the operating system240 and application programs 236 may be stored in the RAM 225 and/orhard disk 227 of the computer system 220.

A user may enter commands and information into computer system 220through input devices, such as a keyboard 255 and a mouse 242. Otherinput devices (not shown) may include a microphone, joystick, game pad,touch pad, satellite dish, scanner, or the like. These and other inputdevices are often connected to processing unit 222 through a USB(universal serial bus) 246 that is coupled to the system bus 223, butmay be connected by other interfaces, such as a serial port interface, aparallel port, game port, or the like. A display device 247 may also beconnected to system bus 223 via an interface, such as a video adapter248. In addition to the monitor, personal computers typically includeother peripheral output devices (not shown), such as speakers andprinters.

The computer system 220 may operate in a networked environment usinglogical connections to one or more remote computers 249. Remote computer249 may be another personal computer, a server, a client, a router, anetwork PC, a peer device, a mainframe, a personal digital assistant, aninternet-connected mobile telephone or other common network node. Whilea remote computer 249 typically includes many or all of the elementsdescribed above relative to the computer system 220, only a memorystorage device 250 has been illustrated in FIG. 6. The logicalconnections depicted in the figure include a local area network (LAN)251 and a wide area network (WAN) 252. Such networking environments arecommonplace in offices, enterprise-wide computer networks, intranets,and the internet.

When used in a LAN networking environment, the computer system 220 isoften connected to the local area network 251 through a networkinterface or adapter 253. When used in a WAN networking environment, thecomputer system 220 typically includes a modem 254 or other means forestablishing high-speed communications over WAN 252, such as theinternet. Modem 254, which may be internal or external, is connected tosystem bus 223 via USB interface 246. In a networked environment,program modules depicted relative to computer system 220, or portionsthereof, may be stored in the remote memory storage device 250. It willbe appreciated that the network connections shown are exemplary andother means of establishing a communications link between the computersmay be used.

Program modules may be stored on hard disk 227, optical disk 231, ROM224, RAM 225, or even magnetic disk 229. The program modules may includeportions of an operating system 240, application programs 236, or thelike. A voltage regulation thresholds database 238 may be included,which may include a specification of the range of allowable errorbetween actual and expected voltage for one or more CPUs whose voltageis to be monitored. This database may specify a margin of error such asshown in FIG. 2. A Voltage/VID database 239 may also be included, whichmay include data relating the range of possible VID values andcorresponding expected voltage values for the one or more CPUs. Forexample, the CPU properties database 239 may contain the characteristiccurve or table for each CPU, an example of which is also shown in FIG.2. Alternatively, the voltage regulation thresholds and CPU propertiesmay be contained on a microcontroller that is a component of a voltagemonitoring system according to the invention.

Aspects of the present invention may be implemented in the form ofapplication program 236. Application program 236 may be informed by orotherwise associated with voltage regulation thresholds database 238and/or Voltage/VID database 239. The application program 236 generallycomprises computer-executable instructions for monitoring the dynamicCPU voltage according to the invention.

The terms “comprising,” “including,” and “having,” as used in the claimsand specification herein, shall be considered as indicating an opengroup that may include other elements not specified. The terms “a,”“an,” and the singular forms of words shall be taken to include theplural form of the same words, such that the terms mean that one or moreof something is provided. The term “one” or “single” may be used toindicate that one and only one of something is intended. Similarly,other specific integer values, such as “two,” may be used when aspecific number of things is intended. The terms “preferably,”“preferred,” “prefer,” “optionally,” “may,” and similar terms are usedto indicate that an item, condition or step being referred to is anoptional (not required) feature of the invention.

While the invention has been described with respect to a limited numberof embodiments, those skilled in the art, having benefit of thisdisclosure, will appreciate that other embodiments can be devised whichdo not depart from the scope of the invention as disclosed herein.Accordingly, the scope of the invention should be limited only by theattached claims.

1. A method, comprising: supplying a voltage to a processor in relationto the value of a VID output from the processor; converting an analogvalue of the supplied voltage to a digital value; detecting any changein the value of the VID signal during the analog to digital conversionof the supplied voltage; accepting the digital value of the suppliedvoltage and the value of the VID signal during the analog to digitalconversion unless a change in the value of the VID signal is detectedduring the analog to digital conversion; and computing an error betweenthe accepted digital value of the supplied voltage and a voltageexpected in response to the accepted value of the VID.
 2. The method ofclaim 1, further comprising comparing the computed error with apredefined threshold.
 3. The method of claim 2, further comprising:adjusting one or more processor parameter in response to the computederror exceeding the predefined threshold.
 4. The method of claim 3,wherein adjusting the one or more processor parameter includes reducingthe voltage supplied to the processor, turning off the processor,reducing a processor load on the processor, or shifting processor loadfrom the processor to another processor.
 5. The method of claim 1,further comprising averaging a plurality of the voltage regulationerrors.
 6. A system for monitoring a dynamic processor voltage,comprising: a voltage regulation module for supplying a voltage to aprocessor in relation to a VID generated by the processor; an analog todigital converter for converting an analog value of the supplied voltageto a digital value; a change detection module for detecting any changein the dynamic VID during the analog to digital conversion; and avalidation module for comparing the supplied voltage to a voltageexpected in relation to the VID and computing a difference between theexpected voltage and the supplied voltage.
 7. The system of claim 6,further comprising at least one microcontroller, wherein one or both ofthe analog to digital converter and the change detection module areincluded with the at least one microcontroller.
 8. The system of claim7, wherein the analog to digital converter and the change detectionmodule reside on the same microcontroller.
 9. The system of claim 6,wherein the change detection module comprises a change detection bitselectively resettable by the validation module.
 10. The system of claim6, wherein the change detection module comprises a plurality of latchsettings for storing VID values.
 11. The system of claim 6, wherein theprocessor, voltage regulation module, and voltage monitoring system aredisposed on a common motherboard.
 12. A computer program productcomprising a computer usable medium including computer usable programcode for analyzing a processor voltage supplied to a processor inrelation to the value of a dynamic VID signal output from the processor,the computer program product including: computer usable program code forconverting receiving a digital value resulting from an analog to digitalconversions of the supplied processor voltage; computer usable programcode for detecting any change in the value of the VID signal during theanalog to digital conversion; computer usable program code for acceptingthe digital value of the supplied processor voltage and the value of theVID signal during the analog to digital conversion unless a change inthe value of the VID signal is detected during the analog to digitalconversion; and computer usable program code for computing an errorbetween the accepted digital value of the supplied processor voltage anda voltage expected in response to the accepted value of the VID.
 13. Thecomputer program product of claim 12, further comprising: computerusable program code for comparing the computed error with a predefinedthreshold.
 14. The computer program product of claim 12, furthercomprising: computer usable program code for generating a signal inresponse to the computed error exceeding the predefined threshold. 15.The computer program product of claim 14, further comprising: computerusable program code for adjusting one or more processor parameter inresponse to the signal.
 16. The computer program product of claim 12,wherein the computer usable program code for adjusting the one or moreprocessor parameter includes computer usable program code for reducingthe voltage supplied to the processor, turning off the processor,reducing a processor load on the processor, or shifting processor loadfrom the processor to another processor.
 17. The computer programproduct of claim 12, further comprising computer usable program code foraveraging a plurality of voltage regulation errors.
 18. The computerprogram product of claim 12, further comprising computer usable programcode for statistically analyzing the plurality of voltage regulationerrors.